Step ladder



FIG. 1 is a front perspective view of a step ladder showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a elevational view taken from the right side thereof, a view taken from the left side being a mirror image thereof;

FIG. 5 is a top view thereof; and,

FIG. 6 is a bottom view thereof. 

The ornamental design for a step ladder, as shown and described. 